1  /* mpz_sqrt(root, u) --  Set ROOT to floor(sqrt(U)).
       2  
       3  Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2005, 2012, 2015 Free
       4  Software Foundation, Inc.
       5  
       6  This file is part of the GNU MP Library.
       7  
       8  The GNU MP Library is free software; you can redistribute it and/or modify
       9  it under the terms of either:
      10  
      11    * the GNU Lesser General Public License as published by the Free
      12      Software Foundation; either version 3 of the License, or (at your
      13      option) any later version.
      14  
      15  or
      16  
      17    * the GNU General Public License as published by the Free Software
      18      Foundation; either version 2 of the License, or (at your option) any
      19      later version.
      20  
      21  or both in parallel, as here.
      22  
      23  The GNU MP Library is distributed in the hope that it will be useful, but
      24  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
      25  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
      26  for more details.
      27  
      28  You should have received copies of the GNU General Public License and the
      29  GNU Lesser General Public License along with the GNU MP Library.  If not,
      30  see https://www.gnu.org/licenses/.  */
      31  
      32  #include <stdio.h> /* for NULL */
      33  #include "gmp-impl.h"
      34  
      35  void
      36  mpz_sqrt (mpz_ptr root, mpz_srcptr op)
      37  {
      38    mp_size_t op_size, root_size;
      39    mp_ptr root_ptr, op_ptr;
      40  
      41    op_size = SIZ (op);
      42    if (UNLIKELY (op_size <= 0))
      43      {
      44        if (UNLIKELY (op_size < 0))
      45  	SQRT_OF_NEGATIVE;
      46        SIZ(root) = 0;
      47        return;
      48      }
      49  
      50    /* The size of the root is accurate after this simple calculation.  */
      51    root_size = (op_size + 1) / 2;
      52    SIZ (root) = root_size;
      53  
      54    op_ptr = PTR (op);
      55  
      56    if (root == op)
      57      {
      58        /* Allocate temp space for the root, which we then copy to the
      59  	 shared OP/ROOT variable.  */
      60        TMP_DECL;
      61        TMP_MARK;
      62  
      63        root_ptr = TMP_ALLOC_LIMBS (root_size);
      64        mpn_sqrtrem (root_ptr, NULL, op_ptr, op_size);
      65  
      66        MPN_COPY (op_ptr, root_ptr, root_size);
      67  
      68        TMP_FREE;
      69      }
      70    else
      71      {
      72        root_ptr = MPZ_NEWALLOC (root, root_size);
      73  
      74        mpn_sqrtrem (root_ptr, NULL, op_ptr, op_size);
      75      }
      76  }